These types of devices are used as portable inhalation devices which permit the user to inhale a medicated vapour spray where the spray may include powders, liquids or gasses.
These types of devices are usually used by people suffering from asthma and other respiratory diseases or disabilities having difficulty breathing from time to time. Depending on the activity level of the person in question, the breathing difficulties may be more or less severe. Also inflammations or other infections or secondary diseases in the respiratory system can further aggravate the difficult breathing situation.
Asthma inhalation devices function in a way whereby the user/patient when needing to inhale the medication places the asthma inhalation device with a mouthpiece in the patient's mouth and thereafter activates a button. By depressing the button a canister inside the device is activated such that a medication dose stored in the valve system in the canister is dispensed through the mouthpiece to the patient.
A number of medications are available in order to alleviate these symptoms and substantially restore the individual's ability to breathe to a normal stable situation.
Although there are a number of different ways in which to take medications for alleviating the problems mentioned above, one of the more common types is to have the medication mixed with an aerosol propellant in a canister. The canister in then placed in an inhalation device whereafter the individual suffering from breathing problems can insert a mouthpiece into the mouth and by depressing the canister in the device dispense a dose of the medication directly into the airways.
The canister is usually placed upside down in the device, see for example EP 476991, such that the dispensing nozzle and/or the rim, i.e. the ferrule as well as the stem of the canister, are pointing downwards in the inhalation device. The stem rests on a seat and is guided such that upon depression of the canister by the user's hand into the device, the nozzle will be depressed and due to the overpressure created by the propellant in the canister, a dose will be sprayed into the user's mouth. The user will then inhale the aerosolised medication directly into the lungs.
The device disclosed in EP 476991 further discloses a pivotable member, which in a closed position covers the mouthpiece and in an active position is pivoted into a position where the member engages the bottom of the canister and acts as a lever arm for depressing the canister.
It is a requirement that canisters of this type are fitted with a valve system whereby depression of the canister and thereby dispensing of medication through the stern/nozzle is provided such that only one single dose per compression will be dispensed.
Conventional dispensers are usually two-piece structures consisting of a housing which contains the mouthpiece which is also adapted to receive the aerosol canister wherein the medication is contained. The medication is contained in the canister under pressure due to the presence of an aerosol. The canister is inserted into the housing so that the dispensing nozzle of the canister is pointed downward and oriented towards the mouthpiece provided on the housing as is the case in EP 476991. The opposite end of the canister usually projects upwardly and outside the housing. The user can place the housing between the thump and forefinger and use the thump and forefinger or the thump and fingers to force the canister downward and in this way release a dose of the medication into the mouthpiece and thereby inhale it into the airways and lungs.
For individuals suffering from mild forms of asthma or other breathing disabilities, depressing the canister into the device and thereby dispensing a dose does usually not cause a problem. However, a large number of the users of these types of devices are also suffering from other debilitations such as rheumatism or arthritis. Furthermore, small children needing asthma medications may also find it difficult to grip the prior art devices as mentioned above in that their hand are physically to small in order to be able to grip around the device and exert the necessary force in order to dispense a dose. A number of devices are therefore proposed which should aid especially users with reduced physical ability to depress the canister in order to dispense a dose. Such devices are presented in U.S. Pat. No. 6,397,837, EP 476991 and U.S. Pat. No. 4,834,083 wherein the traditional inhalation device can be equipped with a lever arm device mounted on the traditional inhalation device.
One problem associated with some of the devices mentioned above is that the lever arrangement either must be installed before every dispensing of a dose. This can cause serious problems for the user in that usually when a dose is needed, the user's ability to breathe is hampered and the stress level for the user is therefore increased. In order to assemble the device such that a dose can be dispensed, more parts have to be relocated and assembled on the device. Another problem is that for a host of users it is desirable to carry the device around with them such that a dose can be dispensed whenever needed i.e. in the office; on the bus etc. For this purpose the users often carry their dispensing device in a pocket or in a small handbag. With the lever arm arrangement according to the prior art mentioned above there is a tendency that the lever arm may become stuck since it projects outside the general geometry of the device itself as seen in for example U.S. Pat. No. 6,397,837 and EP 476991. This in turns means that either the device will be broken off and therefore not function or the lever arm arrangement will be disassembled causing extra trouble for the user when a dose needs to be dispensed.
For a number of users suffering from diseases where the medication is dispensed in the manner described above they will have different canisters containing different concentrations of the medication or even different types of medication for different diseases. The canisters and/or devices are often colour-coded in order to provide information about the medications contained in the canister. It is however a problem for the user always to have the correct canister mounted in the device as well as some of the devices are made in such a way that it is impossible to recognise the colour-coding on the canister as usually a large part of the canister is placed inside the dispensing device. It is therefore foreseeable that a situation can arise where a person suffering from any of the debilitations mentioned above will find him/herself in a situation with the wrong medication and further might inadvertently dispense a dose of a wrong medicament due to the inability of recognising the canister in the device.
Depressing the canister in order to dispense a dose can require an amount of force which for some users creates uncertainty whether a dose has been fully dispensed or not, due to the user's limited strength. As a number of the users as explained above can have limited force in their hands it becomes increasingly difficult for these persons to dispense doses when needed.
Recently the legislative bodies in the different countries have made moves to ban the CFC-gasses which are traditionally used as aerosols in canisters of this type. CFC-gasses are being replaced by a new family of gasses known as HFA-gasses. These gasses when used as aerosols/propellants require that the gaskets and the valve arrangement in the canister are made in a different manner. For the user the result is that a higher force is needed in order to compress the canister into the inhalation device whereby the nozzle is sufficiently compressed for it to dispense a dose of the medication. As a number of the users as explained above can have limited force in their hands it becomes increasingly difficult for these persons to dispense doses when needed. A further consideration both for producers and for the users of this type of device is the hygienic circumstance in which the device as a whole but especially the mouthpiece is manufactured, handled, stored and kept by the user.
Some patients suffering from asthma or other respiratory diseases often suffer from other related diseases such that it is important that the mouthpiece is kept as clean as possible.
In order to protect the mouthpiece, it is customary to provide a loose cap which snugly fits onto the mouth piece. This cap however, has a tendency to become lost, damaged or otherwise not fulfil its function. In order to alleviate this it has been suggested in the art to fasten the cap to the device itself, for example by means of a strap or to arrange a hinge such that the cap member can be pivoted into a closed position as is the case I EP 476991. In all the prior art devices where attachment means have been provided for keeping the cap in close proximity to the device as such, the cap can obstruct the usability of the device and hamper the dispensation of a medication dose.
A different solution is proposed in U.S. Pat. No. 4,834,083, where a cap is not provided as such. The space in which the nozzle and valve of the canister is placed is separated from the outside by a slidable closure gate.
The device as disclosed in U.S. Pat. No. 4,834,083 further discloses an arrangement for avoiding accidental dispensation of a dose. When the canister is placed inside the device, the lever arm is pivoted into a closed position covering the canister. The lever arm is provided with two projections—a latch and a stop. When closing the lever, the latch engages a hook section provided in the housing. The stop projects through an aperture in the housing for engagement with a catch. In order to prepare the device for use the gate shall be raised, whereby the gate shall deflect the stop from its engagement with the catch. As the lever is depressed, both the latch and the stop may be further deflected due to engagement with the housing in order for the lever to be able to move downwards. A number of drawbacks are connected with this construction. As the stop is arranged in a aperture in the housing and the gate acts on the stop adjacent the aperture, the forces needed for deflecting the member sufficiently are high. The deflection is, furthermore, limited by the latch which altogether hampers the depression of the canister. The space between the stop and the latch is very limited and if foreign matter becomes stuck, the operation of the device is severely obstructed.
On the other hand, after a number of deflections the stop may have attained a substantial permanent deflection such that accidental dispensation of a dose may occur. Productionwise is may also be difficult to control the process as the latch and stop members must be separated and precisely spaced and curved in order to be able to cooperated with corresponding elements in the housing.
In order to be able to describe the canister in detail and how the different parts and sections of the device are arranged in relation to each other, the relative terms “inside”, “outside”, “up”, “down”, “in front of” and “behind” shall be interpreted as imagining the device in the user's mouth in the use situation i.e. in a situation where a user is standing vertically and inserts the device having the canister in a substantially vertical position with the stem and nozzle section and ferrule of the canister placed such that the stem and nozzle can dispense a dose out through the mouthpiece. In this position the canister containing the medication is above the stem. Consequently, the bottom of the canister is the end with the ferrule and the stem/nozzle. The opposite end is designated the top. In front of the canister, means that it is close to the user's face i.e. on the same side as the mouthpiece, and behind the canister is to be understood as being away from the user's face. Inside the housing is to be interpreted as being within the volume comprised within the housing. Horizontal is consequently defined in relation to the above described use position.